Johnson Jerald said: "I think she's the hot sauce on the meal. Where you're like, 'Wait a minute, did somebody just put hot sauce on that? Oh, it's not that hot. Oh - yes it is!'

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"So I think she's going to make it not as comfortable as it has been and I think that's great. I love a good challenge. I think she loves a good challenge too. I think that's where she's coming in and mixing up that crew."

Johnson Jerald added that she is interested in the relationship between Gates and Castle (Nathan Fillion), saying: "I'm certain he's used to being praised to no end and now it's someone who's like, 'You're only here for one reason and if it was up to me, you wouldn't be'. So it will be like a love-hate kind of relationship."

Johnson Jerald also hinted that Gates and Beckett (Stana Katic) may clash in future episodes.

"As a female, you either have a whole bunch of female friends or none," she said. "And it's a challenge where you're trying, [like] a competition, 'OK, I'm really good at my job, too', 'Well I'm good at my job, too!' So you have that battle - that unspoken battle."